package nsa

import (
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"strings"
)

var database *sql.DB
var eventmap = make(map[string]int)

type Logger struct {
	ip string
}

func NewLogger(ip string) *Logger {
	return &Logger{
		ip: ip,
	}
}

func (l *Logger) getEventID(event string) int {
	evID, ok := eventmap[event]
	if !ok {
		logErr("Event %s does not exist.", event)
		return 0
	}
	return evID
}

func (l *Logger) getJSON(data interface{}) string {
	jsonStr, err := json.Marshal(data)
	if err != nil {
		logErr("%v", err)
		return ""
	}
	return string(jsonStr)
}

func (l *Logger) insertEvent(id int, data string) {
	if database == nil {
		return
	}
	_, err := database.Exec(
		"INSERT INTO nsa.events (type, data, client_ip) VALUES ($1, $2, $3);",
		id, data, l.ip)
	if err != nil {
		logErr("%v", err)
	}
}

func (l *Logger) Log(event string, data interface{}) {
	if database == nil {
		return
	}
	go func() {
		id := l.getEventID(event)
		if id == 0 {
			return
		}
		d := l.getJSON(data)
		if d == "" {
			return
		}
		l.insertEvent(id, d)
	}()
}

func logErr(msg string, params ...interface{}) {
	fmt.Fprintf(
		os.Stderr,
		"NSA: Error: %v\n",
		fmt.Sprintf(msg, params...))
}

func Init(db *sql.DB) error {
	err := db.Ping()
	if err != nil {
		return err
	}
	database = db
	return nil
}

func SetEvents(events []string) error {
	if database == nil {
		return errors.New("not initialized")
	}
	rows, err := database.Query("SELECT id, name FROM nsa.event_types;")
	if err != nil {
		return err
	}
	defer rows.Close()
	for rows.Next() {
		var id int
		var name string
		rows.Scan(&id, &name)
		eventmap[name] = id
	}
	newEvents := []string{}
	params := ""
	paramNum := 1
	for _, event := range events {
		e := strings.ToUpper(event)
		if _, ok := eventmap[event]; ok {
			continue
		}
		newEvents = append(newEvents, e)
		params += fmt.Sprintf("($%d),", paramNum)
		paramNum++
	}
	if len(newEvents) > 0 {
		params = params[0 : len(params)-1]
		values := []interface{}{}
		for _, event := range newEvents {
			values = append(values, event)
		}
		rows, err = database.Query(
			fmt.Sprintf(
				"INSERT INTO nsa.event_types (name) VALUES %s RETURNING id;",
				params),
			values...)
		if err != nil {
			return err
		}
		defer rows.Close()
		i := 0
		for rows.Next() {
			var id int
			rows.Scan(&id)
			eventmap[newEvents[i]] = id
			i++
		}
	}
	return nil
}